1. Field of the Invention
The present invention relates to chain forming apparatus and method for using same, and more particularly, to a chain forming apparatus and method for producing oriented, one way links in a chain.
2. Description of the Prior Art
A one way chain is a chain which has oriented, one-way links which are employed to secure an oriented link within a pocket of an associated tensioning device. In such a tensioning device, a chain link is received within a pocket which positions the received link so that the generally parallel straight side portions thereof are at an obtuse angle to the longitudinal axis of the next link closest to a load.
The pockets in the tensioning device are intended to position the arcuate end portion of the link nearest the load of the received link at, or near the longitudinal axis of the tensioning device.
If properly employed, the positioning of the arcuate end portion of the line nearest the load of the received link concentrates the forces on the tensioning device near its longitudinal axis.
If the chain is improperly connected to the tensioning device by placing the arcuate end portion furthest from the load of the received link near the longitudinal axis of the device, the line of forces creates a moment on the device which is undesirable and greater bending forces are concentrated on the chain link.
Neither the chain link nor the tensioning devices have as high a strength with improper loading; and improper loading can result in an unanticipated and premature release of the load.
It has been recognized that an oriented link which only can be received in the pocket in one direction PG,3 can be used to ensure that the arcuate end portion of the link nearest the load was correctly positioned. This oriented link can be established by providing a pear-shaped link or by putting a large single weld on one of the straight portions of a link adjacent to the arcuate end. However, it is desirable to produce an oriented link on a conventional roll forming machine to reduce the price of the chain and to enable different types and sizes of chain to be used.
Heretofore various methods and apparatus have been proposed for processing chain. Examples of such methods and apparatus can be found in the following U.S. Patents:
______________________________________ U.S. PAT. NO. PATENTEE 1,812,052 Lamb 2,895,290 Devonshire et al. 3,913,374 Esser et al. 4,428,186 Hedren et al. ______________________________________
The Lamb U.S. Pat. No. 1,812,052 discloses a method of making chain and apparatus therefor. This patent discloses an apparatus for beading and forming wire from coiled stock into a completed chain.
The Devonshire et al. U.S. Pat. No. 2,895,290 discloses a chain link having identification and a replacement gauging means. This patent discloses a method for permanently making chains for purposes of visual identification by placing a symbol on one leg or straight side portion of a link by compressing and deforming each link.
The Esser et al. U.S. Pat. No. 3,913,374 discloses an apparatus for bevelling wire blanks. This patent discloses an apparatus which bevels wire blanks to ensure a better weld when such blanks are subsequently formed into a chain.
The Hedren et al. U.S. Pat. No. 4,428,186 discloses a chain making apparatus. This patent discloses an apparatus for the manufacture of several chains at a time by flash welding.
The apparatus of the present invention is used to manufacture a one-way chain which has oriented links. The one-way function is achieved by forming a protuberant detent on each straight side portion of a link near one arcuate or rounded end of the link. The forming of the protuberances, the width sizing of each link and the trimming of the interior weld of each link is performed by the apparatus in conjunction with a conventional automatic roll forming machine which greatly reduces manufacturing time and cost of the chain.
Moreover, the method of the present invention differs from the previously proposed method by providing a method for mass producing oriented, one-way links from a regular chain.